I'm working on an RSO/01. It's the Chinese boxing of the Italeri kit and comes with the Voyager PE set, plus I'm using the old Friul tracks. The new ones have wire for pins and corrected sprockets, the old you crimp together. Although the new are more accurate (the old being a bit wide, etc), I'm happy with the old--the difference in width is small, while the new set has noticeable oversized track pin heads.
I noticed that the axle bolt on each roadwheel is often secured with a strap held in by opposing lug nuts, so I shaved off some lug nuts, added brass strips, and replaced the lug nuts.
I've started accurizing the cab and detailing its interior. While it's an impressively accurate kit for its day (originally a Peerless/Max kit), it needs lots of fixing. Here I added some of the stamped shapes to the inside of the cab.

Here I started fixing the engine cooling vents, which don't match the engine air duct in the cab.

I've found lots of photos online, plus I've got Allied-Axis #20, but still I've got questions. I plan on building this as an early example at Kursk in panzer grey, towing a sIG 33 (since I have an extra). Does anyone know have references that might help me? I'm coming up short on units using the RSO/01 (1st Ski Jaeger Bde of course, and photos labelled Artillerie Abteilung 425), or towing a sIG 33.